Driving force transmission device

Abstract

A baffle plate including a body portion, a cover portion and a seal member, a final gear and a driven sprocket disposed in an accommodating chamber of the baffle plate, an oil pump serving as a source of oil for lubrication, and an oil pan are provided. At least one of the body portion, the cover portions and the seal members includes a material that shrinks as the temperature of the oil decreases. The baffle plate is dimensioned such that a gap is sealed by the seal member when the temperature of the oil is equal to or higher than a predetermined oil temperature and an aperture is formed when the temperature of the oil is less than the predetermined oil temperature. The gap is the gap between an inner circumference of an outer wall portion of the body portion and each of a base portion of the cover portion and a base portion of the cover portion.

The invention claimed is: 
     
       1. A driving force transmission device comprising:
 a baffle plate portion including a pair of baffle plates and a sealing member disposed in a region between the pair of baffle plates; 
 a rotating member disposed within a rotating member chamber that is a space surrounded by the baffle plate portion; 
 an oil pump that serves as a source of oil for lubrication supplied to the rotating member; and 
 an oil pan in which the oil is stored and from which the oil pump sucks the oil, wherein 
 at least one of the following (i) or (ii) includes material configured to shrink as an oil temperature decreases:
 (i) one of the pair of baffle plates, or 
 (ii) the other one of the pair of baffle plates (iii), and 
 
 the baffle plate portion is dimensioned such that an outer peripheral edge of the seal member is pressed against an outer wall portion of the baffle plate portion covering an outer periphery of the rotating member when the oil temperature is equal to or higher than a predetermined oil temperature and an aperture is formed in the region between the pair of baffle plates to stop sealing by the seal member when the oil temperature is less than the predetermined oil temperature. 
 
     
     
       2. A driving force transmission device as defined in  claim 1 , wherein
 the material is a polymer material. 
 
     
     
       3. A driving force transmission device as defined in  claim 2 , wherein
 the polymer material is a resin material or a rubber material. 
 
     
     
       4. A driving force transmission device as defined in  claim 2 , wherein
 the baffle plate portion has a rib formed of the polymer material. 
 
     
     
       5. A driving force transmission device as defined in  claim 4 , wherein
 the rib is provided a position away from the aperture. 
 
     
     
       6. A driving force transmission device as defined in  claim 4 , wherein
 a plurality of ribs are provided. 
 
     
     
       7. A driving force transmission device as defined in  claim 4 , wherein
 a slit is provided at the rib. 
 
     
     
       8. A driving force transmission device as defined in  claim 4 , wherein
 the rib is disposed outside the rotating member chamber.